The minimum usually is 2.5k. You can probably go up to 10k.
Lets assume you have a 2500ohm pot, you want 10v maximum across the pot.
This results in a current of I=E/R = 10/2500 = .004 or 4ma.
Now you have 2 volts to lose somewhere, so put a resistor in series at the 12v end.
The resistor will have to drop 2v at 4ma, R=E/I 2/.004 = 500ohms.
For any other pot value, use the same formula, the input impedance seen by the pot slider can usually be ignored for this calculation.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.